Blackboard.



Patented Dec. 24, |901.

' S. BDLLINS.

BLACKBOARD. (Application rled Apr. 24, 1901.)

(No Model.)

mwlpaegim UNITED STATES PATENT OEEICE.

SAMUEL COLLINS, OF LANS BOTTOM, WEST VIRGINIA.

BLACKBOOARD.

SPECIFICATION forming part of Letters Patent No. 689,539, dated December24, 1901.

Application filed April 24, 1901. Serial No; 57,285. (No model.)

To all whom it may conterr:

Be it known that I, SAMUEL CoLLINs, a citi- YZen of the United States,residing at Lanes Bottom, in the county of Vebster and State of WestVirginia, have invented a new and useful Blackboard, of which the`following is a specication.

This invention relates to adj nstable blackboardsg and it has for itsobject to provide a device of this natu re which may be easily andquickly adjusted to the proper height to suit the conditions under whichit is used, further objects and advantages of the inventionhavingreference to the specific construction and arrangement ofparts,which will be understood from the following description.

In the drawings forming a portion of this specification, and in whichlike numerals of reference indicate similar parts in the several views,Figure 1 is an elevation showing the board and its supporting-frame withthe mechanism for raising and lowering it. Fig. 2 is a side elevationofthe structure shown in Fig. 1. Fig. 3 is a transverse section througha portion of the board and one of the guideposts and showing thedovetail connection therebetween. Fig. et is a detail view showing theclip connection between the board and a post and the position of theretaining-spring.

Referring now to the drawings, there is shown a frame including upperand lower beams 5 and 6 and connecting cross-pieces or4 nprights 7 andS, and attached to the front faces of the beams by means of the brackets9 are the posts 10 and 11, which are cylindrical and in the front-facesof which are formed longitudinal slots 12, which are broadened 'inwardlyor dovetailed. The board, which is shown at 13, has the battens 14secured against its rear face and which battens have the longitudinalribs 15, which are broadened at their rear edges to correspond to theslots 12, in which they are slidably engaged, so that the board may havea vertical movement, `while it will be held against outward displacementfrom the supporting-frame..

The board is held normally and yieldably raised by means of helicalsprings 16, which are disposed upon the posts and rest with their lowerends against the brackets on the lower beam, while the upper ends of thesprings rest against the clips 17, which are engaged with tlie board andencircle the posts. These clips also serve as an additional means forpreventing outward displacement of the bottom of the board. To lower theboard against the tendency of the springs, two pulleys 18 and 19 aresecured to the upper beam 5, and two other pulleys 20`and 2l are securedto the lower beam 6. A line 22 is attachedto the rear of the board andis taken downwardly and. around pulley 20, then upwardly and over pulley19, then downwardly and around pulley 21, and then upwardly and overpulley 1S, fromwhence it is taken laterally beand is engaged with awinding-drum 22,

rights of the supporting-frame. The winding-drum carries a gear 24,withwhich meshes a pinion 25 upon a shaft 25', which carries also acrank-wheel 2G, provided with a ratchet 27 and with ahandle 28. Byrotating the crank-wheel the winding-drum is rotated to wind up the lineand lower the board, and when the crank-wheel is released the resiliencyof the springs returns the board to its raisedposition. Thus by holdingthe crankwheel at the properpoint the board may be held at acorresponding elevation. T0 thus hold the crank-wheel, a pawl 2S isprovided and is pivoted on .the frame of the kwinding-drum and whichlpawl is adapted for en-V wheel. It the crankewheel be rotated to lowerthe board, the springs will be compressed, as above stated, and iteisthen only necessary to release the ratchet by pressing upon the outerend of the pawl to raise its engaged end, when thecrank-wheel will turnand will permit the winding-drum to rotate to release the line andpermit the board to rise.

It will be understood that in practice modifications of the specificconstruction shown may be made and that anysuitable materials andproportions may be used without departing from the spirit of theinvention.

What is claimed is- 1. In a device of the class described, thecombination with a supporting-f rame including posts having dovetailgrooves, of a board having dovetail ribs slidably engaged with thegrooves, clips carried by the *board and encircling the posts, springsdisposed upon mounted in a frame 23 upon one of the 11pgagement with theratchet on the crank` hind `the board and beyond the end thereof IOO theposts and bearing against the frame and clips, and means for moving andholding the board against the tendency ofthe springs.

2. A device of the class described comprising a frame including postshaving longitud-inal grooves which are broadened inwardly, a boardhaving ribs which are broadened outwardly and slidably fitted in thegrooves, clips engaged with the board and encircling the posts, helicalsprings upon the posts and bearing against the clips to hold the boardyieldably in raised position, pulleys upon the frame, a line engagedwith the board and passed around the pulleys to move the board againstthe tendency of the springs, a Winding-drum to which the line isconnected to be SAMUEL COLLINS.

Witnesses:

G. F. WILKINS, R. C. FERGUSON.

